configuration to actually specify the name of the networks that should not be used for
Live Migration. Therefore, if you have a specific network to be used for Live
Migration, it should be placed in the following PowerShell command (in the example,
my Live Migration network is named Migration Network):
Get-ClusterResourceType -Name "Virtual Machine" | Set-ClusterParameter -Name MigrationExcludeNetworks -Value ([String]::Join(";",(Get-ClusterNetwork
| Where-Object {$_.Name -ne "Migration Network"}).ID))
In Windows Server 2008 R2, only one concurrent Live Migration could be performed
between any two nodes in a cluster. For example, a Live Migration could be performed
between node A and node B, and a separate Live Migration could be performed
between node C and node D, but it would not be possible to have two Live Migrations
between A and B, nor would it be possible to have a Live Migration between node A
and node B and between node A and node C. Failover Cluster Manager would also not
allow the queuing of Live Migrations (although SCVMM did). The logic was that a
single Live Migration would saturate a 1Gbps network link and most datacenters were
1Gbps. This has changed in Windows Server 2012 to allow multiple concurrent Live
Migrations between hosts up to the limit you specify as part of the Live Migration
configuration, which I cover later in this chapter. Windows Server 2012 Failover
Cluster Manager also introduces the concept of queuing Live Migrations that cannot
be actioned immediately.
In Windows Server 2012 and above failover clusters, the Live Migration process
remains the same. Virtual machines are always created on shared storage. However,
instead of the virtual machines having to be stored on cluster storage, they can be
stored on an SMB 3 file share that has been configured so that each node in the
cluster and the cluster account have full permissions. Note that if you are storing
virtual machines in a cluster on an SMB 3 file share, it’s important that the file share
is not a single point of failure; it should be a Scale-out File Server, which itself is using
Cluster Shared Volumes for the shared storage. This also allows the use of Shared
VHDX.
Windows Server 2012 Live Migration Enhancements
One of the key reasons that Live Migration was restricted to within a cluster in
Windows Server 2008 R2 was that the storage between the source and the target must
be available, which meant that Cluster Shared Volumes had to be used. Windows
Server 2012 introduced the ability to use an SMB file share to store virtual machines,
enabling hosts outside of a cluster to view the same storage, provided they had the
right permissions. This enabled a new type of Live Migration in Windows Server 2012:
SMB is leveraged to store the virtual machine, and then the Live Migration technology
is leveraged to move the virtual machine state and memory before the handle of the
virtual machine’s resources on the SMB share switches to the target node.
In a cluster environment, the network used for Live Migration is configured as part of